NOUS42 KTBW 221600 PNSTBW FLZ039-042-043-048>052-055>057-060>062-065-231200- PUBLIC INFORMATION STATEMENT NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL 1200 PM EDT MON SEP 22 2008 ...AUTUMN HAS OFFICIALLY BEGUN, SO WHEN IS IT GOING TO COOL OFF?... ASTRONOMICALLY SPEAKING AUTUMN BEGAN AT 11:44 AM TODAY...BUT ACROSS WEST CENTRAL AND SOUTHWEST FLORIDA THE TEMPERATURES ARE ANYTHING BUT FALL-LIKE. WE'VE HAVE HAD A RESPITE FROM SOME OF THE HIGHER HUMIDITY OVER THE LAST FEW DAYS WITH DEW POINTS EACH AFTERNOON FALLING INTO THE MID 60S...BUT HIGH TEMPERATURES HAVE CONTINUED IN THE UPPER 80S TO LOWER 90S. DURING MOST YEARS WE DO NOT SEE THE FIRST SHOT OF COOLER DRIER AIR UNTIL THE MIDDLE OF OCTOBER...ALBEIT USUALLY IS RATHER SHORT LIVED LASTING ONLY A DAY OR TWO...WITH THE REAL COOL DOWN NOT OCCURRING UNTIL NOVEMBER. A GOOD WAY TO EXAMINE THE TIMING OF THE FIRST COOL DOWN IS BY LOOKING AT OVERNIGHT LOW TEMPERATURES. THE OVERNIGHT LOW TEMPERATURES ARE HIGHLY DEPENDENT ON A FEW FACTORS...NOT THE LEAST BEING THE AMOUNT OF CLOUD COVERAGE...HOW STRONG THE WINDS ARE AND THE AMOUNT OF MOISTURE IN THE AIR NEAR THE GROUND MEASURED BY LOOKING AT THE DEW POINT. IN GENERAL OVERNIGHT LOW TEMPERATURES CANNOT FALL BELOW THE DEW POINT...THEREFORE IF THE DEW POINTS ARE STILL IN THE UPPER 60S TO LOWER 70S AS THEY ARE NOW...THEN THE OVERNIGHT LOW TEMPERATURES WILL MOST LIKELY ALSO BE IN THE UPPER 60S TO LOWER 70S UNLESS A COOL FRONT MOVES THROUGH DURING THE NIGHT. SO TO SEE WHEN THE FIRST COOL FRONT MOVES ACROSS THE REGION LETS LOOK AT THE DATES WHEN LOW TEMPERATURES FALL BELOW DIFFERENT THRESHOLDS AT SOME LOCATIONS. DATE OF FIRST LOW TEMPERATURE <= 60 DEGREES FAHRENHEIT RECORDS LOCATION EARLIEST LATEST AVERAGE BEGAN CHIEFLAND 5 SE AUG 27 1969 OCT 25 1959 SEP 28 1956 INVERNESS 3 SE SEP 09 1997 OCT 25 1959 OCT 07 1948 BUSHNELL 2 E SEP 09 1997 NOV 03 1969 OCT 06 1948 BROOKSVILLE CHIN HILL SEP 16 2001 NOV 04 1900 OCT 10 1892 ST LEO SEP 14 2001 NOV 08 1919 OCT 11 1895 TARPON SPRINGS SEP 19 1981* NOV 15 1919 OCT 13 1892 TAMPA INTERNATIONAL SEP 19 1981 NOV 15 1919 OCT 17 1890 ST PETERSBURG OCT 01 1920 DEC 04 1986 OCT 27 1915 PLANT CITY SEP 15 1918 NOV 05 1900 OCT 10 1893 LAKELAND SEP 19 1981 NOV 14 1946 OCT 18 1946 BARTOW SEP 19 1981 NOV 14 1946 OCT 14 1892 WINTER HAVEN SEP 19 1981 NOV 14 1946 OCT 19 1941 PARRISH SEP 19 1981 NOV 03 2007 OCT 15 1958 SARASOTA-BRADENTON SEP 20 1981 NOV 02 1994 OCT 13 1948 WAUCHULA 2 N SEP 19 1981 NOV 07 1941 OCT 13 1933 AVON PARK 2 W SEP 20 1981 NOV 14 1946 OCT 16 1902 ARCADIA SEP 16 1962 NOV 19 1911 OCT 12 1901 ARCHBOLD BIO STN SEP 08 1997 NOV 04 2007 OCT 06 1969 VENICE SEP 27 1956 NOV 05 1998* OCT 18 1956 PUNTA GORDA 4 ESE OCT 02 2001* NOV 05 1985 OCT 19 1965 FORT MYERS OCT 01 1920* DEC 03 1986 OCT 27 1902 --------------------------------------------------------------------- DATE OF FIRST LOW TEMPERATURE <= 55 DEGREES FAHRENHEIT RECORDS LOCATION EARLIEST LATEST AVERAGE BEGAN CHIEFLAND 5 SE SEP 10 1963 OCT 27 1994 OCT 07 1956 INVERNESS 3 SE SEP 16 1956 NOV 05 1985 OCT 16 1948 BUSHNELL 2 E SEP 27 1956 NOV 05 1950 OCT 16 1948 BROOKSVILLE CHIN HILL SEP 16 2001 NOV 14 2003* OCT 20 1892 ST LEO SEP 19 1981 NOV 15 1919 OCT 21 1895 TARPON SPRINGS SEP 20 1981 NOV 25 1922 OCT 22 1892 TAMPA INTERNATIONAL SEP 22 1897 NOV 25 1948 OCT 27 1890 ST PETERSBURG OCT 01 1920 DEC 15 1998* NOV 07 1915 PLANT CITY SEP 20 1981 NOV 22 1986 OCT 20 1893 LAKELAND OCT 03 1984 NOV 25 1948 OCT 24 1946 BARTOW SEP 22 1913* NOV 25 1922 OCT 24 1892 WINTER HAVEN OCT 04 1974 DEC 03 1986 OCT 28 1941 PARRISH OCT 02 1984 NOV 14 2003 OCT 22 1958 SARASOTA-BRADENTON OCT 04 1974 NOV 24 1994 OCT 25 1948 WAUCHULA 2 N SEP 27 1956 NOV 22 1986 OCT 24 1933 AVON PARK 2 W OCT 01 1920 NOV 25 1948* OCT 27 1902 ARCADIA OCT 01 1920 DEC 04 1986 OCT 25 1901 ARCHBOLD BIO STN SEP 29 2006 DEC 03 1986 OCT 20 1969 VENICE OCT 03 1974 DEC 03 1986 OCT 29 1956 PUNTA GORDA 4 ESE OCT 10 2000 DEC 04 1986 OCT 31 1965 FORT MYERS OCT 01 1920 DEC 11 1994 NOV 05 1902 --------------------------------------------------------------------- DATE OF FIRST LOW TEMPERATURE <= 50 DEGREES FAHRENHEIT YEAR RECORDS LOCATION EARLIEST LATEST AVERAGE BEGAN CHIEFLAND 5 SE SEP 20 1981 NOV 06 1998 OCT 15 1956 INVERNESS 3 SE OCT 02 2001 NOV 21 1986 OCT 25 1948 BUSHNELL 2 E OCT 02 1984 NOV 14 2003 OCT 24 1948 BROOKSVILLE CHIN HILL SEP 22 1897 NOV 30 1958 OCT 30 1892 ST LEO SEP 22 1897 NOV 30 1958 OCT 31 1895 TARPON SPRINGS OCT 01 1920 DEC 05 1919 NOV 02 1892 TAMPA INTERNATIONAL OCT 11 1906 DEC 15 1998 NOV 08 1890 ST PETERSBURG OCT 24 1937 JAN 02 1987 NOV 20 1915 PLANT CITY OCT 04 1929 NOV 25 1948 OCT 29 1893 LAKELAND OCT 10 2000 DEC 11 1958 NOV 05 1946 BARTOW OCT 01 1920 DEC 16 1998 NOV 02 1892 WINTER HAVEN OCT 14 1977 DEC 03 1986 NOV 07 1941 PARRISH OCT 10 1976 DEC 16 1998 OCT 22 1958 SARASOTA-BRADENTON OCT 14 1977 DEC 04 1986 NOV 03 1948 WAUCHULA 2 N OCT 14 1977 DEC 04 1986 NOV 01 1933 AVON PARK 2 W OCT 04 1929 DEC 12 1994 NOV 05 1902 ARCADIA OCT 01 1920 DEC 12 1994 NOV 02 1901 ARCHBOLD BIO STN OCT 09 1972 DEC 12 1994 OCT 30 1969 VENICE OCT 14 1977 DEC 12 1994 NOV 09 1956 PUNTA GORDA 4 ESE OCT 14 1977 JAN 02 1987 NOV 11 1965 FORT MYERS OCT 01 1920 DEC 11 1994 NOV 05 1902 * LAST OF MULTIPLE OCCURRENCES LOOKING AT THE TABLES ABOVE WE DO SEE THAT THE AVERAGE TIME OF THE FIRST COOL FRONT APPEARS TO BE DURING MID-OCTOBER. THIS IS WHEN TEMPERATURES GENERALLY FALL INTO THE MID 50S ACROSS INLAND PORTIONS OF THE NATURE COAST AND BELOW 60 DEGREES ELSEWHERE ACROSS WEST CENTRAL AND SOUTHWEST FLORIDA. THE ONLY EXCEPTION IS NEAR THE COAST WHERE THE WATER KEEPS TEMPERATURES HIGHER AND THESE AREAS TAKE LONGER TO FALL BELOW 60 DEGREES, AS SEEN AT ST. PETERSBURG. AS A SIDE NOTE, FOR THOSE WHO MISS OR WOULD LIKE TO SEE WHERE THE FOLIAGE HAS BEGUN TO CHANGE COLOR ACROSS THE UNITED STATES, VISIT THE USDA FOREST SERVICE WEB SITE LISTED BELOW. HTTP://WWW.FS.FED.US/NEWS/FALLCOLORS/ FOR MORE LOCAL CLIMATE INFORMATION...PLEASE SEE OUR WEB PAGE AT HTTP://WEATHER.GOV/TAMPABAY AND CLICK ON THE "LOCAL" LINK UNDER THE CLIMATE SUBSECTION ON THE LEFT SIDE OF THE PAGE. $$ PRC